Triangle Fans (Direct3D 9)

A triangle fan is similar to a triangle strip, except that all the triangles share one vertex, as shown in the following illustration.

illustration of a triangle fan

The system uses vertices v2, v3, and v1 to draw the first triangle; v3, v4, and v1 to draw the second triangle; v4, v5, and v1 to draw the third triangle; and so on. When flat shading is enabled, the system shades the triangle with the color from its first vertex.

The following illustration depicts a rendered triangle fan.

illustration of a rendered triangle fan

The following code shows how to create vertices for this triangle fan.

    float x,y,z;

CUSTOMVERTEX Vertices[] = 
    { 0.0, 0.0, 0.0},
    {-5.0, 5.0, 0.0},
    {-3.0,  7.0, 0.0},
    { 0.0, 10.0, 0.0},
    { 3.0,  7.0, 0.0},
    { 5.0,  5.0, 0.0},

The code example below shows how to render this triangle fan in Direct3D 9 using IDirect3DDevice9::DrawPrimitive.

// It is assumed that d3dDevice is a valid
// pointer to a IDirect3DDevice9 interface.
d3dDevice->DrawPrimitive( D3DPT_TRIANGLEFAN, 0, 4 );

Triangle fans are not supported in Direct3D 10 or later.